The translucent, sea-dwelling invertebrate, called Bathochordaeus charon, was identified recently off the coast of Monterey, California, by scientists using a remotely operated vehicle (ROV). Though B. charon was first discovered a century ago, no one had managed to confirm its existence in all those years, Rob Sherlock, a scientist at the Monterey Bay Aquarium Research Institute who found the creature, told Live Science in an email.
B. charon belongs to a group of sea creatures known as larvaceans — normally teensy, millimeter-size creatures whose bodies resemble a tadpole's, with a large "head" (actually a trunk) and a tail, Sherlock said.
|A giant larvacean, Bathochordaeus charon, that has discarded its mucus feeding filters and is swimming freely in the open ocean.|
If a passing squid or fish crashes through the house, or big particles clog the feeding tube, larvaceans simply move on and build another house. Without their houses, they cannot eat, Sherlock said.
The first report of B. charon's existence came in 1899, when professor Carl Chun of Leipzig University came across one in the south Atlantic Ocean while leading the Valdivia Expedition, a German mission aimed at exploring the deep sea. Chun believed the creature welled up from the deepest depths of the ocean, so he named the larvacean after Charon, who in Greek mythology ferries the souls of the dead across the river Styx, the researchers reported Aug. 16 in the journal Marine Biodiversity Records.
In the decades that followed, several other naturalists reported spotting giant larvaceans, though only a few were captured alive and described thoroughly. In 1936, for instance, British marine biologist Walter Garstang collected a set of giant larvaceans that differed from Chun's, and they were classified as a new species, Bathochordaeus stygius.
Because the two sets of specimens were similar and Chun's originals were lost to history, scientists eventually began to wonder whether Chun's originally described B. charon was actually the same species as B. stygius. One famous larvacean expert even suggested combining the two species names, Sherlock said. Part of the difficulty in capturing these creatures is that they don't fare well in the trawling nets typically used to collect specimens, Sherlock said.
Sherlock and his colleagues happened upon the new species when the team's ROV, called Doc Ricketts, was exploring the waters of Monterey Bay. As soon as they saw it, the crew carefully collected it in a sealed, thermally insulated container.
"Since the vehicle was recovered some tens of minutes later, the animal was alive, in fantastic shape, and we preserved it right away in order to send it to the Smithsonian," Sherlock said. "We had no idea, until we looked more closely at the specimen, that we had actually found B. charon, the species first described over a hundred years ago."
Genetics and analysis of physical features confirmed the find, Sherlock said. It was official: There really were two distinct species of giant larvacean — B. stygius and B. charon.
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